CELLS. SILICA. 
53 
5 
£ 
that live almost entirely on raw rice; 
examples are found in the skulls of 
Malays in the Museum of the College 
of Surgeons. This condition of the teeth 
frequently enables us to distinguish the 
animal or vegetable nature of the food 
by which the individual has been 
supported. 
In the husk of the rice, the woody fibres 
are also coated with silica. In most 
£ specimens the woody fibres are abundant, 
£ some of them, as seen in Fig. 38, present- 
ing peculiar serrated margins somewhat 
like those of the fibres of the crystalline 
lens of the cod-fish ; others, as shown at 6, 
are smooth. 
As I have already stated, the modifi- 
cations of the epidermic cells of plants partake largely 
of the siliceous deposit, and this is particularly the case 
with the hairs or setae which stud the surface of the 
husk of the oat, wheat and other grains. I may 
here refer to a very interesting pathological circum- 
stance in connexion with these minute and seemingly 
insignificant hairs. The occurrence of intestinal con- 
cretions of anomalous character, and of no ordinary 
size, was at one time far from uncommon in this 
country, especially in the north of England and in 
Scotland, and many such specimens are preserved in 
the Museum of the College of Surgeons. Some of 
them are of considerable bulk. One of these was 
Portions of 
woody fibres 
from the husk 
of the Rice . 
